1. Field of the Invention
The present invention relates to an actuator device which is applicable to a display device and which is also applicable to various applications including an optical modulator, a variable capacitor, etc.
2. Description of the Related Art
It is known in the art that an actuator device having a plurality of actuators can be applied to a display device, and can also be applied to various applications including an optical modulator, a variable capacitor, etc. (see Japanese Laid-Open Patent Publication No. 11-339561, for example). With regard to the display device, for example, the applicant of the present application has proposed a novel display device in order to achieve the following advantages:
(1) A clearance (gap) between an optical waveguide plate and a picture element assembly can easily be formed, and can be formed uniformly over all pixels.
(2) The size of the gap can easily be controlled.
(3) The optical waveguide plate can be prevented from sticking to the picture element assembly, and the response speed can effectively be increased.
(4) The contact surface of the picture element assembly (the surface thereof contacting the optical waveguide plate) can smoothly be formed in order to introduce light efficiently into the picture element assembly when the picture element assembly contacts the optical waveguide plate.
(5) The response speed of pixels can be maintained.
(6) A uniform level of luminance can be obtained over all pixels.
(7) The luminance of pixels can be increased.
As shown in FIGS. 52 and 53, a display device 200 has an optical waveguide plate 204 into which light 202 is introduced, an actuator substrate 208 facing one surface of the optical waveguide plate 204 and having as many actuators 206 as the number of pixels, picture element assemblies 210 formed on the actuators 206 of the actuator substrate 208, and spacers 212 disposed between the optical waveguide plate 204 and the actuator substrate 208 in regions other than the picture element assemblies 210 (see, for example, Japanese Laid-Open Patent Publication No. 2003-161896). Light shield layers 218 are interposed between the optical waveguide plate 204 and the spacers 212.
Applications using piezoelectric actuators are disclosed in Japanese Laid-Open Patent Publication No. 11-252333, Japanese Laid-Open Patent Publication No. 2003-52181, Japanese Laid-Open Patent Publication No. 2000-314381, Japanese Laid-Open Patent Publication No. 2003-74475, and WO 02/084751 A1.
In the display device 200, one pixel may be made up of six actuators positioned in two rows and three columns. If one actuator 206 is defective in such a configuration, then a spot corresponding to that actuator 206 is displayed as a black or white dot regardless of an image displayed by the display device 200, tending to cause a disadvantage to increase the image quality.
Specifically, even if one actuator is defective in the conventional actuator device, then since the defective actuator adversely affects the quality of the actuator device, it tends to pose a limitation to increase the yield. Another problem is that the area of a region that is displaced by an actuator, i.e., an effective area, cannot be increased.